Synthesis of 1,4-dihydropyridine and polyhydroquinoline derivatives via Hantzsch reaction using nicotinic acid as a green and reusable catalyst

A rapid, efficient and eco-friendly protocol has been developed for the preparation of various 1,4-dihydropyridine and polyhydroquinoline derivatives in the presence of nicotinic acid as a green and dual catalyst under solvent-free conditions. In this reaction, nicotinic acid shows a highly catalytic nature, easy to handle procedure, short reaction time, recycle exploitation and excellent isolated yields. Furthermore, the H-1 and C-13 chemical shift and X-ray spectra values together with the structural parameters of 1,4-dihydropyridine and polyhydroquinoline have been computed and the scaled values have been compared with the corresponding experimental NMR and X-ray spectra. As a result, the calculated H-1 and C-13 chemical shift and X-ray spectra show a good agreement with the experimental results. (C) 2018 Elsevier B.V. All rights reserved.